Engines, including diesel engines, gasoline engines, and gaseous fuel-powered engines are used to generate mechanical, hydraulic, or electrical power output. In order to accomplish this power generation, an engine typically combusts a fuel/air mixture. With the purpose to ensure optimum combustion of the fuel/air mixture and protect components of the engine from damaging extremes, the temperature of the engine and air drawn into the engine for combustion must be tightly controlled.
An internal combustion engine is generally fluidly connected to several different liquid-to-air and/or air-to air heat exchangers to cool both liquids and gases circulated throughout the engine. These heat exchangers are often located close together and/or close to the engine to conserve space on the machine. An engine driven fan is disposed either in front of the engine/exchanger package to blow air across the exchangers and the engine, or between the exchangers and engine to suck air past the exchangers and blow air past the engine, the airflow removing heat from the heat exchangers and the engine.
Although this cooling arrangement may minimize the likelihood of engine overheating and improve combustion in extreme hot conditions, it may do little to protect the engine and optimize combustion during operation in extreme cold conditions. In extreme cold conditions, engines can be difficult to start and oil that lubricates components of the engine can be so viscous that significant friction within the engine is generated and damage to the engine may occur. In addition, when the air drawn into the engine is too cold, combustion of the fuel/air mixture may be poor resulting in poor load acceptance, white smoke production, and poor fuel efficiency.
One way to improve engine operation and extend component life of the engine in cold extremes is disclosed in Japanese Patent Publication 2002-021653 (the '653 publication) by Shinichi published on Jan. 23, 2002. The '653 publication describes a diesel engine having a two-step inlet air heat exchanger with a cooling section and a heating section. The heating section is supplied with hot coolant from the engine's jacket water circuit, while the cooling section is supplied with relatively cold coolant. An inlet air temperature regulating valve is located within a coolant passageway of the cooling section, and another is located within a coolant passageway of the heating section. Both valves are controlled to regulate a flow of coolant through the cooling and heating sections in response to a temperature of the engine's inlet air and a load on the engine. That is, the flow rate of cold cooling water delivered to the cooling section is increased during times of heavy engine load and/or hot inlet air, and the flow rate of hot cooling water delivered to the heating section is increased during times of low engine load and/or cold inlet air, both flow rates being regulated to achieve a relatively constant desired temperature of the inlet air.
Although the diesel engine of the '653 publication may benefit some from tightened control of inlet air temperatures, the benefit may be limited. That is, the heating section of the '653 publication may only add heat to the inlet air when the engine's jacket water is already warm. When the engine is cold, such as when first started or when operating in extreme cold conditions, the temperature of the jacket water may be insufficient to raise the inlet air temperature to the desired value. As a result, operation at startup and continued operation in cold conditions may be less than optimal.
The disclosed engine system is directed to overcoming one or more of the problems set forth above.